Psychology: scientific study of people, the mind, and behaviour.
Focusing on how people feel, think, behave, believe, interact
The Scientific Method
Started with empiricism: school of philosophy that says that knowledge is gained
through experience, observation, and experiment.
This information is referred to as data: considered empirical because it can be
measured and evaluated statistically.
Empirical evidence is different from anecdotal evidence as anecdotal cannot be
translated into quantifiable form.
Scientific method is crucial as it minimizes bias: unfair practices that discriminate
against others. The method provides rules for collecting data and for evaluating results.
What is a scientific question?
Philosophers claim that there are two types of questions, referred to as is-ought
‘Is’ questions: can be answered by facts or empirical data, and these answers
are independent of social, cultural, political, and religious preference.
‘Ought’ questions: influenced by beliefs that reflect ideology, politics, law, etc.
Science cannot provide any direct, definitive answers to these questions.
Theory: coherent set of propositions that are used as principles to describe, understand,
and explain psychological/behavioural phenomena.
Often addresses questions of ‘how’
Theory to Testable Hypothesis
Testable hypothesis: framed as a statement, often in form of a prediction that is made
prior to the actual collection of data.
Also referred to as a priori: exists before experimentation or observation.
Post hoc hypothesis: hypotheses formulated after the data are collected and analyzed.
This is an issue for the scientific method as they increase the chance of error or
bias. The more you look, the more likely that you will find something. By basing a
hypothesis off an answer, incorrect hypotheses may be viewed as true.
These kinds of hypotheses need statistical adjustment in order to be viewed as a
significant finding. Variables and Measurements
Variable: any characteristic that can take on different values or can vary across
Can include age, gender, height, weight etc. or any other attribute that can
assume multiple values or can vary in people.
Scientific method requires objective measurement of identifiable and specifiable
variables. If something cannot be measured, then it cannot be investigated scientifically.
Systematic Observation and Data Collection
Population: any entire collection of people, animals, plants, or things. These can all be
referred to as units, from which information can be collected.
Sample: A group of units selected from a larger group (the population)
A researcher always tries to maximize generalizability: the extent to which findings that
are derived from a sample can be applied to a wider population
Sample selection is important because if done incorrectly, it can lead to bias.
Case studies can be flawed if cases are selected based on preconceived ideas.
This can lead to sample bias: some members of the population are less likely
than others to be included in a study.
Evaluating Evidence and Theory
Scientific method uses statistics to test relationships between and among objective,
quantifiable measures that are derived from either experimentation or observation.
Statistics are computed on the sample.
All statistics are based on probability and they all use the same criterion for evaluation.
Question asked and answered by statistics is: what is the probability that the
results were obtained by chance?
If the statistical analysis shows that the obtained results are highly unlikely due to
chance then the predicted relationship is considered to be highly likely.
If the statistical analysis shows that the obtained results are highly likely due to
chance then the predicted relationship is considered to be highly unlikely.
Reliability and Validity
A reliable study is one that produces data that can replicated: repeated with the
same results Validity: the extent to which a study provides a true measure of what it is meant to
How a study sample is selected from a population and how representative it is
can influence validity.
In evaluating validity, you look for confounds/confounding variables: unwanted sources
of influence that can be viewed as a viable alternative explanations for the results of a
In many studies, researchers use a control variable in order to measure an
unwanted source of influence that could invalidate the conclusions of a study.
This goal is to rule out the effect of a control variable on the effects of a study.
Scientific Method (in a chart)
Observing and Thinking
Formulate a Question
Develop a Hypothesis
Interpret with Caution
Conduct a Study
Methods and Tools of Psychological Research
Def.: restricted to studies in which participants are randomly assigned to groups, where
one or more variables are manipulated.
Researcher designs an experiment in which a particular aspect of the study is
systematically altered or manipulated.
Independent variable: element of the study that is systematically manipulated, changed,
Dependent variable: the observed effect, result, or outcome that is measured in
response to a systematic change in the independent variable.
Random assignment: Helps to ensure that research participants are similar prior to the manipulation of
the independent variable.
Three key variables
Independent variable Dependent variable
(Manipulated) (Measured effect)
Def.: investigations that aim to examine the effects of an independent variable that
cannot be directly manipulated or randomly assigned on a dependent variable.
Examples of independent variables that cannot be manip